The invention pertains to safety apparatus for the detection of an impending vehicular collision and for the reliable and automatic operation of protective devices in the event of a collision and more particularly concerns radio receiver apparatus for utilizing reflected base band signals for the generation, according to the certainty of an impending collision, of control signals for the reliable operation of passenger protective devices.
2. Description of the Prior Art
In the prior art, base band transmitter-receiver systems for the protection of vehicle occupants have generally sought to use inexpensive and trouble-free components with a view of ensuring long-lifed and reliable operation of the apparatus. For these and other reasons, a logical choice for the base band transmitter has been that it be based upon a self-synchronizing, mechanically operated switch, such as a conventional mercury wetted reed switch. Such an arrangement is described in the G. F. Ross, K. W. Robbins U.S. Pat. application Ser. No. 380,628 for a "Closed Loop Gain Control Tunnel Diode Base Band Object Detector," filed July 19, 1973 and assigned to the Sperry Rand Corporation now U.S. Pat. No. 3,858,204. Mercury wetted reed switches are low in cost and are otherwise suitable for relatively low duty cycle operation. However, operation with external synchronization at high duty cycles is desirable for more precise range detection, and enhanced dependability and longer life are also particularly needed in the transmitter-receiver system.